The Worcester Redevelopment Authority is moving toward taking two properties valued at more than $500,000 as the first step of a sprawling revitalization effort, planning to use eminent domain if necessary.

The city agency has begun the process of potentially use eminent domain to acquire two small side-by-side Main Street buildings around the corner from Worcester Common, a year ago this month since the City Council approved a revitalization plan authorizing the redevelopment authority to take by eminent domain properties within a 118-acre zone that stretches from downtown to the Canal District.

The dilapidated properties include the Great Wall Chinese restaurant at 521 Main St. and a MetroPCS cellphone store at 517 Main St. The restaurant has been closed since part of a wall fell down there last month.

"Both are in an interesting situation," said Vincent Pedone, who chairs the WRA board of directors. The owners of both properties have failed to improve the sites over the years, he added. "They can't get these properties rehabbed."

The adjoining sites are part of a large 20-year downtown urban renewal plan, from just past Front Street in the north to the area around the intersection of Southbridge Street and Quinsigamond Avenue, including many vacant or contaminated parcels like the Wyman-Gordon site. In all, the zone includes 380 properties covering around 67 businesses and 214 condominium units.

A study conducted for the city found the zone to be hurt by crime - both real and perceived - a lack of higher-quality office space, a high retail vacancy rate and a shortage of attractions to bring visitors downtown.

As a necessary first step, the authority will seek two appraisals of each property before what could be use of eminent domain to force the property owners to sell to the city. Eminent domain, which can be controversial, is the path of last resort for the city, said Michael Traynor, Worcester's top development official as CEO of WRA.

The Great Wall site, at 521 Main St., was built in 1930, is owned by Mindy Jiang Realty Trust and was last assessed at $296,900, according to city records. The MetroPCS site, at 517 Main St., was built in 1955 and is owned by James Isperduli of Paxton, who died in April, and is assessed at $210,500. Both have less than 10,000 square feet of gross space. Neither entity could be reached for comment.

Both properties are eyed by the city for first-floor commercial floor and upper-floor residences.

The two sites are among six were singled out by the city for rehabilitation under the revitalization plan because, Traynor said, both have suffered from disinvestment for years. Upper stories in both buildings have been vacant for 15 to 20 years and are out of compliance with today's building codes, he said.

The Great Wall site, known as the Holbrook-Saywer Building, and the Cheney-Ballard Building, as its neighbor is historically known, are both seen as contributing to the area's historical feel and are eligible for inclusion on the state and national registers of historic buildings, according to the city.